Using browser context in evasive web-based malware detection

Abstract

The use of browser context in detecting malware is disclosed. A Uniform Resource Locator (URL) is received from a user and at a client device. The URL is used to request, at the client device, and from a remote server, content. At least a portion of data received from the remote server is provided by the client device to an external scanner. The external scanner is configured to use a browser executed in an instrumented virtual machine environment to analyze the data provided by the client device. A maliciousness verdict is received from the external scanner.

What is claimed is: 
     
       1. A system, comprising:
 a processor configured to:
 receive, from a user, and at a client device, a Uniform Resource Locator (URL); 
 use the URL to obtain, at the client device, and from a remote server, content, wherein the remote server is configured to provide a first version of the content when accessed by a client device, and wherein the remote server is configured to provide a second version of the content when accessed by an external scanner; 
 transmit to the external scanner for analysis by the external scanner, data comprising at least a portion of the content received by the client device from the remote server, wherein the external scanner is configured to use a browser executed in an instrumented virtual machine environment to analyze the data provided by the client device; and 
 receive, at the client device, a maliciousness verdict from the external scanner, and only in the event the maliciousness verdict is benign, allow the client device to render content from the remote server at the client device; and 
 
 a memory coupled to the processor and configured to provide the processor with instructions. 
 
     
     
       2. The system of  claim 1  wherein the processor is further configured to receive, from the external scanner, a request that the client device obtain additional data from the remote server. 
     
     
       3. The system of  claim 1  wherein the client device is further configured to act as a proxy on behalf of the external scanner. 
     
     
       4. The system of  claim 1  wherein the processor is configured to request the content from the remote server using a browser extension configured to retrieve data and provide it to the external scanner without rendering the retrieved data. 
     
     
       5. The system of  claim 1  wherein, in response to receiving the maliciousness verdict, the processor is further configured to store the maliciousness verdict on the client device. 
     
     
       6. A method, comprising:
 receiving, from a user, and at a client device, a Uniform Resource Locator (URL); 
 using the URL to obtain, at the client device, and from a remote server, content, wherein the remote server is configured to provide a first version of the content when accessed by a client device, and wherein the remote server is configured to provide a second version of the content when accessed by an external scanner; 
 transmitting to the external scanner for analysis by the external scanner, data comprising at least a portion of the content received by the client device from the remote server, wherein the external scanner is configured to use a browser executed in an instrumented virtual machine environment to analyze the data provided by the client device; and 
 receiving, at the client device, a maliciousness verdict from the external scanner, and only in the event the maliciousness verdict is benign, allowing the client device to render content from the remote server at the client device. 
 
     
     
       7. The method of  claim 6  further comprising receiving, from the external scanner, a request that the client device obtain additional data from the remote server. 
     
     
       8. The method of  claim 6  wherein the client device is configured to act as a proxy on behalf of the external scanner. 
     
     
       9. The method of  claim 6  further comprising requesting the content from the remote server using a browser extension configured to retrieve data and provide it to the external scanner without rendering the retrieved data. 
     
     
       10. The method of  claim 6  further comprising, in response to receiving the maliciousness verdict, storing the maliciousness verdict on the client device. 
     
     
       11. A system, comprising:
 a processor configured to:
 receive, at an external scanner, from a client device, data received by the client device from a remote server and in response to a request for content made by the client device to the remote server, wherein the remote server is configured to provide a first version of the content when accessed by the client device, and wherein the remote server is configured to provide a second version of the content when accessed by the external scanner; 
 analyze the data using a browser executed in an instrumented virtual machine environment; 
 determine a maliciousness verdict for a URL based at least in part on the analyzed data; and 
 provide the maliciousness verdict to the client device; and 
 
 a memory communication interface coupled to the processor and configured to provide the processor with instructions. 
 
     
     
       12. The system of  claim 11  wherein the processor is further configured to request, from the client device, additional data from the remote server. 
     
     
       13. The system of  claim 12  wherein the processor is configured to use the client device as a proxy to request the additional data. 
     
     
       14. The system of  claim 11  wherein the client device is configured to receive the data from the remote server using a browser extension configured to transmit the data without rendering the received data. 
     
     
       15. The system of  claim 11  wherein analyzing the data includes determining whether additional remote web content is needed to render a page. 
     
     
       16. The system of  claim 11  wherein the instrumented virtual machine environment is configured to hook every API that can load remote web content. 
     
     
       17. The system of  claim 16  wherein the processor is configured to interrupt an attempt to load the remote web content so that the remote web content is requested from the client device. 
     
     
       18. A method, comprising:
 receiving, at an external scanner, from a client device, data received by the client device from a remote server and in response to a request for content made by the client device to the remote server, wherein the remote server is configured to provide a first version of the content when accessed by a client device, and wherein the remote server is configured to provide a second version of the content when accessed by an external scanner; 
 analyzing the data using a browser executed in an instrumented virtual machine environment; 
 determining a maliciousness verdict for a URL based at least in part on the analyzed data; and 
 providing the maliciousness verdict to the client device. 
 
     
     
       19. The method of  claim 18  further comprising requesting, from the client device, additional data from the remote server. 
     
     
       20. The method of  claim 19  further comprising using the client device as a proxy to request the additional data. 
     
     
       21. The method of  claim 18  wherein the client device is configured to receive the data from the remote server using a browser extension configured to transmit the data without rendering the received data. 
     
     
       22. The method of  claim 18  wherein analyzing the data includes determining whether additional remote web content is needed to render a page. 
     
     
       23. The method of  claim 18  wherein the instrumented virtual machine environment is configured to hook every API that can load remote web content. 
     
     
       24. The method of  claim 23  further comprising interrupting an attempt to load the remote web content so that the remote web content is requested from the client device.